JP4933982B2 - Condensate structure and construction method. - Google Patents

Description

  The present invention relates to the structure and construction method of a condensate structure.

If the flow of groundwater is interrupted due to the construction of an underground structure, the groundwater will not flow downstream.
In such a case, as a method of maintaining the flow of downstream groundwater, a method of constructing a condensate well and injecting upstream groundwater into the condensate well is used as a condensate method, recharge method, etc. Are known.
Japanese Patent Laid-Open No. 06-306842. Japanese Patent Laid-Open No. 06-220866.

The conventional condensate method and recharge method as described above have the following problems.
<1> Since the soil particles in the aquifer are forcibly moved outward by the water injection, by continuing the water injection, the soil particles in a certain range are pushed away from the well for a certain distance. Therefore, it is inevitable that the clogging is caused by closing the gap of the aquifer around the well. Since this is an injection from a "dot" -shaped well, the groundwater flow rate tends to be excessive, and the groundwater forcibly moves the soil particles around the well and spreads over a certain range. This is to cause clogging. In addition, it is also known that it is caused by chemical reaction such as floating impurities, organisms such as bacteria, and rust.
<2> As a result, due to secular change due to use, there is a problem that it is impossible to secure the rise of groundwater to a predetermined water level on the downstream side.
<3> Conventionally, it has been necessary to frequently perform cleaning work every time a condensate well is clogged, and a large maintenance cost has been required.
<4> Condensate wells during cleaning work cannot be filled with water, so a large number of wells had to be provided.
<5> Since the wells and the wells are independent of each other and independent, the water injection capacity of the wells varies depending on the ground properties around the installation location, and the reliability may be lacking.
<6> If a condensate well with a large diameter is constructed, the water injection capacity is improved and clogging can be suppressed, but a large site is required for this purpose. Therefore, it was difficult to install a large-diameter condensate well in an urban area where the available land is limited.

In order to solve the above problems, the structure of the condensate structure of the present invention is a condensate structure for replenishing underground water into the ground with a lowered water level, and comprises a perforated pipe and a permeable wall. The permeable wall is constructed by filling the excavation part installed in the ground with a granular material, and a plurality of perforated pipes are installed inside the permeable wall. Introduced , at least one of the multiple perforated pipes is configured as a condensate perforated pipe, and the other perforated pipe is configured as an auxiliary perforated pipe. Sometimes, the auxiliary perforated pipe functions as a water injection pipe, a dormant pipe, or a pumping pipe, and when pumping from the condensate perforated pipe, the auxiliary perforated pipe functions as a water injection pipe. It is.
The condensate structure construction method of the present invention is a condensate structure construction method for replenishing underground water into the ground with a lowered water level, and comprises a perforated pipe and a permeable wall, and excavates the ground. and established the perforated tube of the plurality of the excavation was, around the perforated pipe by filling the granules constitute the permeability wall, perforated pipe is on its side opened a water flow space, a plurality At least one of the perforated pipes is a condensate perforated pipe, and the other perforated pipe is configured as an auxiliary perforated pipe. Is configured to function as a water injection pipe, a resting pipe, or a pumping pipe, and at the time of pumping from the condensate perforated pipe, the auxiliary perforated pipe functions as a water injection pipe .

Since the structure of the condensate structure of the present invention is as described above, the following effects can be obtained.
<1> The condensate structure can be effectively utilized by suppressing clogging of the aquifer due to water injection.
<2> Compared with one condensate well, the water flow area is large, so a large water injection capacity can be expected.
<3> The permeable wall is not a flat point like a well but a “wall” that is linear in a plane, so it has directionality, and can be installed with the surface facing the house. The groundwater flow and water level can be controlled according to the conditions.
<4> Since water can be poured in a wide area with respect to the downstream water permeable layer, water can be poured at a moderate flow rate. Therefore, it is difficult for the soil particles to move, and it is possible to keep the balance between the two without inhibiting the outflow of the soil particles that cause the clogging in the aquifer and inhibiting the clogging recovery function.
<5> Because multiple wells are placed inside one permeable wall, if clogging occurs in an aquifer, water is poured from one well and pumped from another. The clogging can be recovered by repeating the work, and the condensate can be continued semipermanently.
<6> Since there are multiple wells, water injection from other wells can be continued even during clogging recovery work in some wells. There is no decline.
<7> Since the condensate structure can be constructed in a planar shape, it does not require a large-diameter site such as a large independent well, and a narrow and narrow site that is relatively easily available can be used effectively. .

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

<1> Overall description.
The condensate structure 1 of the present invention is constituted by a permeable wall 2 and a plurality of perforated pipes 3 arranged inside the permeable wall 2.

<2> Permeable wall 2.
The permeable wall 2 is configured by filling a granulated body 21 inside an excavation part such as a trench excavated in the ground.
As a method for excavating a ditch into the ground, various conventionally known underground wall and pile construction methods and excavators can be employed.

<3> Installation of the perforated tube 3.
A plurality of perforated tubes 3 are installed inside the permeable wall 2.
The perforated pipe 3 is a tubular body such as a steel pipe installed in the permeable wall 2.
This perforated tube 3 has a water flow space 31 on its side surface.
The water flow space 31 is constituted by, for example, a thin window-shaped slit, a circular or square hole, or the like.
The internal dimensions of the water flow space 31 are reduced or a fine net or the like is attached to the water flow space 31 so that surrounding soil particles do not enter from the water flow space 31.

<4> Installation method of the perforated tube 3.
An example of a method for installing the perforated tube 3 inside the permeable wall 2 will be described with reference to FIG.
First, the ground is drilled into a cylindrical shape by a known excavating machine to form a cylindrical hole 4 in the ground.
Collapse of the wall surface of the cylindrical hole 4 is prevented by filling the inside with a self-decomposable stabilizing liquid and its specific gravity.
The mud water inside the cylindrical hole 4 is replaced with a new stabilizing liquid, and the perforated pipe 3 is installed.
And the granular material 21 is thrown into the circumference | surroundings of the perforated pipe | tube 3, only the upper end of the perforated pipe | tube 3 is opened to the ground surface, and the circumference | surroundings are embed | buried with the granular material 21. FIG.
Here, the granular material 21 is, for example, crushed stone, bean gravel, gravel, glass ball, steel ball, concrete recycled material, or the like.
In this way, one water-permeable cylinder formed by surrounding the perforated tube 3 with the granular material 21 is formed in the ground.
Adjacent to the perforated tube 3 is sequentially constructed with a permeable cylinder surrounded by the granular material 21 by the same method.
At that time, a part of the granular material 21 is partially overlapped to ensure the continuity of the granular material 21 layer, and this is configured as the water permeable wall 2.
Water is repeatedly poured and pumped in each perforated tube 3 in a state of being embedded in the permeable wall 2, and cleaning is performed using an open slit or the like.
Thus, it is possible to construct a wall-shaped condensate structure 1 in which a plurality of perforated tubes 3 are embedded in the permeable wall 2.

<5> Condensation process.
The groundwater pumped up at another position is poured into the plurality of perforated pipes 3 embedded in the permeable wall 2 through the above-described processes without pressure or under pressure.
Since the water passage space 31 such as a slit is opened in the perforated pipe 3, the water poured into the inside penetrates the surrounding granular material 21 layer, that is, the inside of the water permeable wall 2 from the water passage space 31, It then invades the surrounding underground aquifer.
In this way, the groundwater level that has been reduced by blocking the groundwater flow due to construction of the underground structure or the like can be raised to a level equivalent to the conventional level.
In the case of the condensate process, not only water is poured into all the perforated pipes 3 but also water is poured into every other perforated pipe 3 according to the required amount of water to be supplied underground. The other perforated tube 3 can be set as the auxiliary perforated tube 3b and can be in a rest state. (Figure 2)

<6> Adjustment of the density of the granular material.
In some cases, the granular material 21 is installed at a uniform density throughout the condensate structure 1, but not only that, but it is “dense” around the perforated tube 3, and at a position away from the perforated tube 3, “ It is also effective to install it roughly.
“Dense” and “coarse” are relative states inside the condensate structure 1 and cannot be specified numerically.
Here, “density” means the size of the gap between the granular materials, and “dense” means that the gap is small.
The following effects can be expected by changing the density of the granular material 21 depending on the location.
That is, if the density of the granular material 21 is constant, the speed of the poured water gradually decreases when the injected water diffuses inside the granular material 21.
Therefore, the density of the granular material 21 is made dense around the perforated tube 3 and is roughly arranged as it goes away.
Then, the hydraulic conductivity and the hydraulic gradient are almost inversely proportional, and a substantially constant flow velocity can be ensured in a wide range.
The flow velocity is the product of the hydraulic conductivity and the hydraulic gradient.
In addition, the water permeability coefficient of the granular material 21 may be, for example, about 10 ⁻¹ cm / sec to 10 ⁻² cm / sec.

<6> Cleaning operation.
The above condensate permeates from the permeable wall 2 having a wide surface into the surrounding ground, so that the water permeates at a low flow rate unlike the conventional independent condensate well.
Therefore, it is possible to suppress the outflow of soil particles that cause clogging in the aquifer, in which the soil particles in the ground are forcibly moved at a large flow rate.
As a result, as described above, clogging is much less likely to occur compared to conventional condensate wells.
However, clogging may occur due to long-term use or rapid rainfall.
In that case, good cleaning can be performed by effectively utilizing the fact that a plurality of perforated tubes 3 are embedded in one permeable wall 2.
For example, as shown in FIG. 3, water is pumped from the condensate perforated pipe 3a, and water is poured into the adjacent auxiliary perforated pipe 3b.
Then, the soil particle group that has been clogged by the flow of groundwater from the condensate perforated pipe 3a is forced to move in the opposite direction, and clogging is eliminated.
Alternatively, as shown in FIG. 4, water is injected from the condensate perforated pipe 3a, and by actively pumping water from the auxiliary perforated pipe 3b that has been in a suspended state, the clogged soil particles are forced. In an unstable state.
Thereafter, pumping water from the condensate perforated pipe 3a and water injection from the auxiliary perforated pipe 3b can be used to remove clogging by removing unstable soil particles. .
In other words, the soil particles are shifted from both sides to apply force to promote movement, and as a result, clogging is eliminated.
In order to eliminate clogging, non-pressurized water, pressurized water, or pressurized air can be used to supply the inside of the perforated tube 3.

<7> The planar shape of the permeable wall 2.
In the embodiment shown in the figure, the condensate structure 1 that is rectangular in plan view has been described. However, the condensate structure 1 in which the perforated pipe 3 is disposed inside the trapezoidal permeable wall 2 in plan view, or the permeate structure that is circular in plan view. A condensate structure 1 in which the wall 2 and a rectangular or trapezoidal permeable wall 2 are combined may be employed.
Further, the condensate structure 1 in which the permeable walls 2 cross in a cross shape in a planar manner can be employed.
Moreover, the condensate structure 1 in which the water-permeable wall 2 continued in a V shape and a polygonal line shape in a plane can also be adopted.

<8> Arrangement of perforated tubes.
In the embodiment of the figure, the case where the perforated pipe 3 is arranged on the central axis of the water permeable wall 2 in a plane has been described.
However, it is also possible to adopt a configuration in which the plane is deviated from the center line of the permeable wall 2 and is biased to the right and left, or alternately arranged on the left and right.
In the case where the perforated pipe 3 is arranged so as to deviate from the center line of the permeable wall 2 in a plane and is biased to one side, the influence on the aquifer outside the permeable wall 2 by water injection and pumping to the perforated pipe 3 The range can be expanded.
As a result, the groundwater flow to the outside of the permeable wall 2 can be suppressed over a wider range.
At the same time, not only the inside of the water permeable wall 2 but also the aquifer outside the water permeable wall 2 can be washed in a wider range.
Further, when the perforated pipes 3 are planarly deviated from the center line of the permeable wall 2 and are alternately arranged in a so-called “staggered” manner, the effect of decentering from the central axis to one side as described above is obtained. It can be obtained on both sides, and an effect that the thickness of the entire permeable wall 2 is expanded can be expected.

Explanatory drawing of the Example of the structure of the condensate structure of this invention. Explanatory drawing of the water injection state at the time of condensate. Explanatory drawing of the state which pumps up and wash | cleans a perforated tube. Explanatory drawing of the state which injects water and wash | cleans a perforated tube. Explanatory drawing of the Example which builds a condensate structure.

Explanation of symbols

1: Condensate structure 2: Permeable wall 3: Perforated pipe 21: Granular body 31: Water flow space 3a: Condensate perforated pipe 3b: Auxiliary perforated pipe 4: Cylindrical hole

Claims (2)

A condensate structure for replenishing underground water into the ground with low water levels,
It consists of a perforated tube and a permeable wall,
The permeable wall is constructed by filling the excavation part installed in the ground with granular material,
Install multiple perforated tubes inside the permeable wall,
The perforated pipe has a water flow space on its side,
At least one of the plurality of perforated pipes is a condensate perforated pipe, and the other perforated pipe is configured as an auxiliary perforated pipe,
When water is injected from the condensate perforated pipe, the auxiliary perforated pipe functions as a water injection pipe, a rest pipe, or a pumping pipe,
When pumping from the condensate perforated pipe, the auxiliary perforated pipe is configured to function as a water injection pipe.
Condensate structure. A method for constructing a condensate structure for replenishing underground water into the ground with a lowered water level,
It consists of a perforated tube and a permeable wall,
Install multiple perforated pipes in the excavated part that excavated the ground,
The perimeter of the perforated tube is filled with granular material to form a permeable wall,
The perforated pipe has a water flow space on its side,
At least one of the plurality of perforated pipes is a condensate perforated pipe, and the other perforated pipe is configured as an auxiliary perforated pipe,
When water is injected from the condensate perforated pipe, the auxiliary perforated pipe functions as a water injection pipe, a rest pipe, or a pumping pipe,
A method for constructing a condensate structure in which an auxiliary perforated pipe is configured to function as a water injection pipe when pumping water from a condensate perforated pipe .

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